var req;

function loadXMLDoc(url,valor)
{
    req = null;
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
        req.onreadystatechange = processReqChange;
        req.open("GET", url+'?ci='+valor, true);
        req.send(null);
    } else if (window.ActiveXObject) {
        req = new ActiveXObject("Microsoft.XMLHTTP");
        if (req) {
            req.onreadystatechange = processReqChange;
            req.open("GET", url+'?ci='+valor, true);
            req.send();
        }
    }
}

function processReqChange()
{
    document.getElementById('atualiza').innerHTML = '<select name=br style=\"WIDTH: 155px; vertical-align:middle;\" class=\"formulario\"><option>Carregando...</option></select>';
    if (req.readyState == 4) {
        if (req.status == 200) {
            document.getElementById('atualiza').innerHTML = req.responseText;
        } else {
            alert("Houve um problema ao obter os dados:\n" + req.statusText);
        }
    }
}

function atualiza(valor)
{
    loadXMLDoc("atualiza.php",valor);
}